% 用平移变换平移法(cycle_spinning)消除gibbs效应
% 编程人 沙威(Wei Sha) 安徽大学(Anhui University) ws108@ahu.edu.cn
clear;
clc;
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%% 1.原始信号
f=50; % 信号频率
fs=800; % 采样频率
N=128; % 采样点
% 信号赋值
n=1:N;
y=sin(2*pi*f*n/fs);
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%% 2.噪声
noise=0.4*rand(1,128);
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%% 3.染噪信号
y_noise=y+noise;
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%% 4.硬消噪采用cycle_spinning技术
% 累加量
z5=zeros(1,N);
% 平移变换频移法
for i=1:N;
z=circshift(y_noise.',i-1).'; % 源信号右平移
[z1,z2]=lwt(z,'db3'); % 小波正变换
z2=zeros(1,N/2); % 高频分量全部为零（主要噪声，硬消噪）
z3=ilwt(z1,z2,'db3'); % 小波反变换
z4=circshift(z3.',-(i-1)).'; % 变换后信号左平移
z5=z5+z4/N; % 平均
end;
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%% 5.显示
error=norm(y-z5)/norm(y); % 相对误差
figure(1);
subplot(2,1,1)
plot(y,'r');
legend('源信号');
subplot(2,1,2);
plot(y_noise);
legend('染噪信号');
figure(2);
subplot(2,1,1)
plot(y,'r');
legend('源信号');
title(error);
subplot(2,1,2);
plot(z5);
legend('消噪后信号');
